Leader’s Guide
W XXX
Backyard STEM
Project Area:
Environmental Science
Creek Cri ers: Home in the River
Inves ga ng Habitats in Streams
Skill Level: Intermediate—
Advanced
Learner Outcomes:
 Be able to describe the
difference between a riffle
and a pool in a creek..
 Be able to measure
stream channel
dimensions.
 Be able to calculate
stream flow rate.
Vocabulary Word
Defini on
Grade 7. Geometry
Benthic Macroinvertebrate
Bridge Math, Applica ons in
Geometry
Riffle
Organisms that do not have a backbone and are visible to the naked eye
and live in the benthos environment; benthos is the bo om of a stream
channel. [abbreviated BMI]
Stream habitat with shallow, fast-moving water and large substrates.
Pool
Stream habitat with deep, slow-moving water and small substrates.
Substrate
Eroded soil that is a pollutant in large quan
Watershed
The land area that drains to a common point.
Tennessee Science
Curriculum Standards:
Success Indicator:
Students can explain the
concept of flowrate in the
units of volume per me.
Science Skills:
Calculate, observe
Life Skills: Observing,
Reasoning
Tags: streams, water flow
rate
Materials:
es.
GO OUTSIDE!
Ask your students:
 Which has a higher flow rate, the
Tennessee River or {insert local creek
name]? How do you know? Talk about how as
small creeks combine to make larger streams and
rivers, the flows combine to make larger flow rates.
Take the students on a
schoolyard tour of a
stream or river! Measure
the dimensions and me a
ping pong ball floa ng
down the channel.
 Use your hand and arm as an example. The fingers
are small creeks (or tributaries) that flow into each
other to make the river, or your arm. Two arms flow
together to make a bigger body of water, or your torso.
Introduce Key Concepts:
Discuss the concept of a watershed: a river is formed by the combina on of many small creeks that
are fed from runoff and groundwater from the land area that drains to that point, or its watershed.
A river’s watershed gets larger as you move downstream, and in turn, a greater amount of water
flows in the river. Use a shoebox to represent a channel and show how a stream has dimensions of
width and depth, just like the shoebox. These stream dimensions affect how water flows and the
type of habitat in the stream. Two types of habitats in rivers are riffles and pools. Riffles are
rela vely short and shallow with fast moving water (or high velocity) and larger substrates (like
gravel, cobbles, and boulders). Insect larvae generally live in riffles in between rocks, along stream
banks, and in natural debris like leaf packs and wood. Pools are rela vely long and deep with slow
moving water (or low velocity) and smaller substrates (like sand and muck). Pools provide fish and
other larger aqua c organisms shelter.
Credits: Andrea Ludwig and Jennifer DeBruyn
The 4-H Name & Emblem is protected under 18 USC 707.
Leader’s Guide
Creek Cri ers: Ecological Detec ves
The overarching goal of this ac vity is to show students that the stream is a complex mosaic of different habitats that are
formed by varying substrates, channel dimensions, and water veloci es. Here, the students will see that channel dimensions
and water velocity will change in any given reach of a stream but flowrate—or the total amount of water moving through the
reach—will stay the same.
Indoor op on:
Materials:
Chairs (at least 4, or preferably more), Stop watch, Measuring tape (at least 25’), Ping pong ball
Procedure: If possible, split class into two groups and perform the ac vity with two simulated channels.

Ask the students to arrange chairs (or two lines of chairs) to act as “creek banks” for the stream channel. Make the channel
as long as possible in your space available (but not longer than the measuring tape).

Ask the students to measure 2-3 places between the banks and calculate an average channel width.

Measure the channel length in feet.

Then ask for a volunteer to act as the “flow.” Ask the students to imagine that the volunteer is the river flow and that the
flow is as deep as the volunteer student is tall. Measure the student’s height, and this becomes the river’s average depth.

Give the flow volunteer the ping pong ball and ask the student to run or walk down the channel to simulate flow “velocity.”
Have the other students use the stop watch to me the student (moving in feet/second). This will simulate flow in a riffle.

Ask the students to fill in the cross-sec on on their
calculate river flow rate.

Repeat this process with a different channel width,
taller height of “flow” volunteer, and ask them to
walk slower through the channel. This will simulate
flow in a pool.
Riffle Cross-sec on: Shallow, fast-moving water.
worksheet and
Outdoor Op on:
Pool Cross-sec on: Deep, slow-moving water.
Materials:
Wading boots (op onal, for all students), Stop watch, Measuring
tape (at least 50’), Metal meter s ck, Ping pong ball
Procedure: Class may work in small groups to measure different areas.

Locate the nearest creek to your classroom.

Iden fy a riffle and a pool, preferably wadeable.

Ask the students to take at least three channel width measurements with the measuring tape and find the average width.

Ask the students to take at least three water depth measurements
with the metal scale and find the average width.

Ask the students to measure out a segment along the bank, approximately 50’ if possible.

Have the students put a ping pong ball in the flow and me how long it takes to travel 50’. Ask them to calculate the flow
velocity ( /s)

Ask the students to calculate the flow rate with the equa on below.

Repeat this process in both a riffle and pool. The calculated flows should be similar.
Equa on with units:
Flow Rate = Average Width x Average Depth x Velocity
Units: Flow Rate (cubic
per second or
3
/s) = Width ( ) x (Depth ( ) x Velocity ( /s)
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Leader’s Guide
Creek Cri ers: Home in the River
Riffle Cross-sec on: Shallow, fast-moving water.
Pool Cross-sec on: Deep, slow-moving water.
To find volume of water passing a point, mul ply the flow
rate ( 3/s) by the me in ques on (e.g. one day, or 86,400
seconds. For example, a stream flowing at 0.5 3/s will pass
43,200 3 of water past a bridge in a single day.
Technology Time!
Comparing and Summarizing Op ons:
Visit the US Geologic Survey (USGS) website and find
real- me stream flow data for streams and rivers
across Tennessee: h p://waterdata.usgs.gov/tn/
nwis/rt. Find a sta on close to your school, click on
the sta on dot on the map, and show students the
flow rate of the stream. Then use the graphing feature to show how the flow rate has changed over
me (e.g. the past 14 days). The graph of flow rate
over me is called a hydrograph. Use this informa on to ask your students ques ons that compare
their stream flow rate data to that of the selected
stream sta on. An example is below.
Ask your students to compare:

How does the flow rate at the USGS sta on
compare with the flow rate measured during the ac vity?

Based on that comparison, which stream is bigger? Which stream has a larger watershed?

How much water will pass under a bridge at the USGS sta on in one day? How does that volume compare to the
water passing by the schoolyard stream?
References:
Adapted from h p://www.rivanna-stormwater.org/aqua c.pdf
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